Do gears need to be broken in?

[Robbie Racer]

I broke a few teeth on my prop shaft drive gear in the lower unit on my B-Max drive. They have the same part number as the XR & XZ gear sets. My mechanic is telling me that new gears have to have a 20 hour break in period. Has anyone else heard of this break in requirement for drive gears? If this is true, that may be the reason for the failure of the first set because I sure didn't break them in easy. They did last for 125 hours though. R/R

[Rayhill]

I changed the gears in my Alpha. This what the Mercruiser Instructions said.
Drive Unit 10-Hour Break in Period
1. Avoid full throttle starts.
2. DO NOT operate at any one constant speed for extended periods.
3. DO NOT exceed 75% throttle during the first 5 hours. During the next 5 hours, operate at intermittent full throttle.
4. Drive unit should be shifted into forward gear a minimum of 10 times during break-in, with run-in time at moderate RPM after each shift.

[TCHB]

Gear sets are set to a load pattern on each tooth. Once the gear pattern is set it is set. Break in does not make sense and I have never heard of a new car, new boat, new anything that call for break in. I took a set of gears out of alpha drive and the wear was hard to see. Good Luck

[RiverToysJas]

TCHB:
...Break in does not make sense and I have never heard of a new car, new boat, new anything that call for break in....Seriously? :confused:
New cars have ALWAYS had break in periods.
RTJas

[gnarley]

Break IN periods??? When I was involved in racing Nothing had a break in period! Engines were built & dyno'd & if proven then were deemed ready. The gear sets for the 9" Ford housings we built in house & ready to run after we built them & checked patterns & preloads as well as gearboxes that were checked then run & of course Everything was always inspected after test runs that were full power tests. Break in periods???
Something doesn't sound right about this break in period??? HEll my own cars are never spared any mercy if they can't take what they are supposed to do & break then they get fixed & hopefully under MFG warranty or parts warranty.

[SchellSchock]

All new boats and motors reccommend a breakin as stated in previous post. I DON"T think this applies to the gear set in the drive as much as to the engine.
I have built my own motors for years and the way I break them in is as follows:
1. Start, adjust as required, runn at 1800 rpm for 1/2 hr. (This is required to allow proper cam breakin).
2. Shutdown, re-torque everything and
3. Start drive as hard is your going to drive it.
If somethin breaks ya didn't build it right in the first place.

[RiverToysJas]

gnarley:
Break IN periods??? When I was involved in racing Nothing had a break in period! I guess we should clearify then. Racing engines are not the same as factory production engines. BUT, even when my Dad was two time national record holder in car drag racing (back in the late 60s), they still broke in motors. They'd run them full throttle for a few minutes and that would be that. Break them in loose and fast. Production cars and boats with modern motors have a longer breakin period, as mentioned above, where you don't run them hard for several hours.
Break in periods are for setting rings on the pistons mainly. Therefore, breaking in gears doesn't sound something you'd need to do. SuperDave013 could probably answer for sure though.
RTJas :D
[ October 18, 2002, 04:24 PM: Message edited by: RiverToysJas ]

[gnarley]

RiverToysJas:
(back in the late 60s), they still broke in motors. They'd run them full throttle for a few minutes and that would be that. Break them in loose and fast.
Break in periods are for setting rings on the pistons mainly. Therefore, breaking in gears doesn't sound something you'd need to do.
RTJas :D I guess I should clarify, I guess you could call dyno time break in or break it time :) check & retorque & drain the engine & yeah production rings & clearances aren't the same but the gear sets didn't get that kind of treatment.
Gear break in?? hmmm

[TCHB]

Gears do not need a break in period. Once you set the load and pattern that it. I talked to one of the John Force crew and he said we set the gears and it is ready to go 200mph or 100,000 miles. When a gear fails it is normally from hardened teeth or not enough meat for the horse power being applied.

[Robbie Racer]

Thanks for the feed back guys. My mechanic said that those break in instructions are directly from Mercury. Anyway, I didn't have the patience to fart around for 20 hours, so I put about 3 hours of break in on them and then went to WOT for a 1/2 mile or so. They didn't break, so maybe they will be okay. I will let you know if I do start having problems with them again though. Thanks again, R/R